ID'ing germanium diodes?

[skiraly017]

I have a box full of what I believe are germanium diodes, most of which have no markings. I can do the "this one looks like a 1N270" or "this one looks like a XXXX" but is there any way to tell for sure? Am I missing some microscopic secret code somewhere? Thanks.

[raulgrell]

Check the forward voltage drop (I think that's what it's called - the voltage it starts conducting at). Generally, Si are around 0.5v, and Ge are around 0.3... That's all I can think of.

[Mark Hammer]

Ditto, although GEs come up with anything between around 180mv-270mv on my meter, depending on the state of the battery and individual differences between diodes.

In our world, differences between various types of GE diodes (270, 60, 34A, etc) are more than likely inaudible.

[skiraly017]

So as long as I've determined whether or not they're germanium, for experimenting purposes just have at it? Thanks.

[Mark Hammer]

Yes.  Differences within diodes (e.g., two 1N34As, one with a 192mv forward voltage, and another with a 235mv forward voltage) will almost always be bigger than differences between diodes (i.e., a 1N270 and a 1N60, each with a 228mv forward voltage).